What are XZ, LZMA, 7z files features and specifications, maximum size, max number of files limit         

7z extension

7Z file extension

what is 7z file format
7-zip file format




7Z extension designates a popular archiving format, created for 7-Zip, a modern file archiver application written by Igor Pavlov and released as freeware and Open Source software. 7-Zip (often incorrectly shortened in 7zip) was originally developed for Microsoft Windows platforms, and ported by p7zip (POSIX-7Zip) project team on Unix platforms.
Spanned multi-volume 7z archives are designated by .001 extension, incrementing file extension numerator for each successive volume of the set - spanned 7z files are split byte-wise, this raw splitting mechanism being compatible with Unix / Linux "split" command and Windows utilities like HJSplit.

PeaZip supports creation and extraction of 7z files: create, open, browse, and extract 7Z archives, convert any supported archive to 7z format and vice-versa.

what are 7z files

what are 7z archives

Maximum number of files in a 7z archive

As maximum number of input files per archive, 7z format allows to store up to 2^32 files (unsigned dword, 4 giga files), exceeding current practical limits.

Maximum size of each file in a 7z archive

7z format can accept input files up to 2^64 bytes in size (16 exabytes, each), far exceeding current needs and limits of most current filesystem implementations.

Maximum total size of 7z archive

7z file can theoretical be up to 2^64 bytes in size (16 exabytes of total size of the archive), far exceeding current needs and capabilities of filesystems as currently implemented.
In example
  • FAT32 filesystem allows files up to 2^32 bytes (4GB in size)
  • NTFS filesystem allows max file size of 2^64 bytes (16 EB) but implementations allows lower maximum sizes, 16 TB in Windows 7, 256 TB in Windows 8, 8 PB in Windows 10
  • exFAT filesystem theoretically allows 2^64 bytes max file size (16 EB), but current implementation is limited to 128 PB

7Z features very high compression ratio through powerful compression algorithms (LZMA, LZMA2, PPMd, BZip2, optionally optimized Deflate), at cost of more memory and CPU intensive compression process - that however can take benefit of parallel computing on modern multicore CPUs.
With Tino Reichardt's codecs for Brotli, Lizard, LZ4, LZ5, and Zstd algorithms, supported by PeaZip, 7z format features faster-than-zip compression / extraction.
On average test cases 7Z format improves compression ratio 30-70% better over classic ZIP format, and 6-7% better than RAR file format (WinRar's native format, proprietary); 7Z compression compares favourably also with new WinZip's ZIPX format in most cases.
7Z format also features native UTF-8 support for filenames, Rijndael / AES encryption, and volume spanning.
XZ extension identify a pure compression format (compresses a single file, without offering option of archiving multiple input file into a single output .xz file), it is based on LZMA/LZMA2 algorithm family, featuring usual 7z-like compression ratio (similar or higher compared to RAR), recently often used on TAR files.

7z format features

When is 7Z format recommended

.7z format is recommended anytime it is important to attain a superior compression ratio, and it is welcome the support for strong encyption to keep archived data private.
It is recommended over zip format when enough time for compression or backup is available, in order to provide better reduction of output size.
PeaZip also supports creation of 7z-format self extracting archives (SFX), so recipient will not need a 7-Zip compatible extractor when receiving one of those self-extracting files.

7z format specifications

Read more about .7z extension: 7-Zip official domain7zip software domain, p7zip projectp7zip POSIX port of 7-Zip for Unix and Unix-like operating systems, 7Z file format specifications7zip specifications, 7Z format Wikipedia entry7zip archive format, PPMdWikipedia prediction by partial matching and LZMA / LZMA2Lempel Ziv Markov chain algorithm data compression algorithms.




Author Igor Pavlov, 1999
2^32 max number of files
2^64 bytes max size (archive, files)

7Z SPEED 7z archives specifications

7z format features average speed, computing intensive compression algorithms are balanced by efficient parallel programming implementation. With codecs providing Brotli, Lizard, LZ4, LZ5, and Zstd methods, speed is excellent, faster than Deflate.

7Z COMPRESSION RATIO what are 7z features

7z archives feature very good compression ratio. Comparable, often better than WinRar's RAR compression, but inferior to state of art PAQ compressor, if enough time is available it is recommended for sparing more disk space as possible when executing backup, compressing disk images or large quantities of data.

7z format features a good array of advanced options. Native support for AES encryption and UTF-8 encoding. Lacks recovery records option available for RAR format.

Synopsis: 7Z file extension. What is 7Z file format, native 7-Zip archives type extension. What are XZ, LZMA, 7z files features and specifications, maximum size, max number of files limit. 7Z format superior compression ratio, compression speed, aes encryption and advanced format options. What is 7z archive format recommended for.

Topics: 7z file extension specs

PeaZip > FAQ > 7Z file extension, 7-Zip archive format


7Z file extension (7-Zip archive format)

BR file extension (Google Brotli compressed format)

BZ2 extension, BZip2 compressed file format

GZ extension, Gzip compressed file format

PAQ, LPAQ, ZPAQ file types

PEA file format specifications

RAR file extension (WinRar archive format)

What are TAR, TGZ, TBZ file types

WIM file extension, Microsoft Windows Imaging format

ZIP file extension

ZIPX file extension (WinZip archive format)

ZST file extension (Facebook Zstandard format)

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